Acyl cyanamides in the form of their alkali salts have been known for a long time. The sodium salt of acetyl cyanamide was described as early at 1878 (J. prakt. Chemie 17 9-11, 1878). The sodium salts of acyl cyanamides of long-chain fatty acids, resin acids or naphthenic acids and their application as soap-like tensides for detergents and wetting agents are known from the British patent specification No. 428,091 of the year 1935 and also from the German patent specification No. 708,428 published in the year 1941. For the preparation of the short- as well as long-chain acyl cyanamides, the respective acid chlorides or acid anhydrides were first reacted with an excess of cyanamide to form the acyl cyanamide, which was then converted to the alkali metal salt in an additional step. A process for the preparation of bifunctional acyl cyanamides, for example adipic acid dicyanamide, by conversion of dicarboxylic acid chloride or dicarboxylic acid ester with cyanamide in alcoholic solution in the presence of substances which have an alkaline reaction and by refluxing is known from the German Offenlegungsschrifts Nos. 20 22 491 and 20 22 492. Similarly, a process for the preparation of sodium formyl cyanamide by conversion of ethyl formate with sodium cyanamide in alcoholic solution by refluxing is described in the German Offenlegungsschrift No. 27 57 586. Finally, substituted cyanoamines, which also include acyl cyanamides of C.sub.1 -C.sub.20 -carboxylic acids in their general formula, are said to be obtainable by conversion of the amines or amides with cyanogen bromide in benzene according to the European Offenlegungsschrift No. 8 475; the corresponding sodium salt is said to be obtained by dissolving in concentrated sodium hydroxide solution, reaction with ammonium carbonate and extraction with isopropyl alcohol.
Although the acyl cyanamides of the long-chain fatty acids thus are soap-like tensides that have been known for almost 50 years, this type of compound has so far not been given any commercial attention as raw material for detergents. Not the least reason for this are the manufacturing conditions according to the known methods, which are unsuitable for large-scale production. These methods were difficult and time-consuming in the case of the fatty acid chlorides or fatty acid anhydrides as starting materials since the free acyl cyanamides are obtained initially and the preparation of the alkali metal salts requires an additional step.